Optical element, replica substrate configured to form optical element

Abstract

An optical element includes a base and many structures arranged at a fine pitch on a surface of the base, each of the structures being in the form of a projection or a depression, in which the structures constitute a plurality of arc tracks, and the structures in every three adjacent rows of the arc tracks are arranged in a tetragonal lattice pattern or a quasi-tetragonal lattice pattern.

1. An optical element comprising:
 a base; and 
 a plurality of structures arranged at a fine pitch on a surface of the base, each of the structures being in a form of a projection or a depression, 
 wherein the structures constitute a plurality of arc tracks, 
 wherein the structures in every three adjacent rows of the arc tracks are arranged in a tetragonal lattice pattern or a quasi-tetragonal lattice pattern, and 
 wherein the tetragonal lattice pattern or the quasi-tetragonal lattice pattern is arranged in directions at 45° to the arc tracks. 
 
     
     
       2. The optical element according to  claim 1 ,
 wherein each of the structures is in the form of a truncated elliptical cone, and 
 wherein the middle of the truncated elliptical cone has a gradient steeper than the gradients of the top and the bottom of the truncated elliptical cone, or 
 wherein the gradient of the top of the truncated elliptical cone is gentle, and the gradient of the truncated elliptical cone is gradually increased with increasing distance from the top of the truncated elliptical cone. 
 
     
     
       3. The optical element according to  claim 1 ,
 wherein the height of the structures in the direction at 45° to the arc tracks is lower than the height of the structures in the radial direction of the arc tracks, or 
 wherein the depth of the structures in the direction at 45° to the arc tracks is smaller than the depth of the structures in the radial direction of the arc tracks. 
 
     
     
       4. A replica substrate configured to form an optical element, comprising:
 a base; and 
 a plurality of structures arranged at a fine pitch on a surface of the base, each of the structures being in a form of a projection or a depression, 
 wherein the structures constitute a plurality of arc tracks, and 
 wherein the structures in every three adjacent rows of the arc tracks are arranged in a tetragonal lattice pattern or a quasi-tetragonal lattice pattern, and 
 wherein the tetragonal lattice pattern or the quasi-tetragonal lattice pattern is arranged in directions at 45° to the arc tracks.